Method of treating concentrates



1?. D. VA`-RE5DALE METHOD 0F TREATING CONLENTHTESA Filed mayn la, 192;;

@Half/'on @par fus lli u e" 1 "gli @e lilith) ih hill assiali ci"enti'yoet-ice.

or 'iii coneoi'liiieffeo comme COMPANY, oi; NEW YORK, n'. Y., Aoonroiififr'ion oF Merrie.

' 'VAN OF LOS ANGELES, CALIFO'RNXA, .ASSIGNR T0 INSPIRTION iiiearion on*minieme eonenlmiietins.

.application 'edlvi'ay 123,

To all 'whom it' may concern it known that l, G'iioizoii D. VANAR new.,izeii. of the United States, residing at Los Anfgelee, in the county ofllos Angeles and Suite oft California, have invented new and 'eisetiilimprovements iii Methods of lieating Concentrates, of which the 'followMinfr ie a specification.

.illy present invention relates 'to a method o treating concentrates toelfeet a comparatively coiiiplete and economical recoveryot' copperthereifroiii.

A V ltiioivii to 'those @killed iii the art lt 'iS .ifell i', in theti'eaoiient. of certain oi'ee or con t-.eiiti'm C: containing; compoundsoli copper, a preliminary roasting may serve a useful purpose, theroasted product then containingan increased relative quantity olSo-called exi dined copper, siiitalile to be .faihseqrentl \f cted toextraction oi' leaching' iii an acid Solution. and electrolysis lieiiig'theieaiit'ei' eiiiplojyei'l lor the deposition ot copper and thesiiiiiiiliaiieoiie regeneration otE the leach iiiipioi'.

l have, however, aeceri'ained that the efi'ect. a preliinioar'irroasting ol the characl'ci' referred to is, in eomeCaeea,iiiiiavoi'alile to a prompt and cimipleielysiiecees'ulpulisequent' hachiiigg` ol' the roasted concentrates; andthat` e ii"pi'ising advantages; may result'. 'li'oiii the aliiirnatii'ecourse lieieiiia'l'tei' di.`- izciilicd, a. ijii'oniiiieiit pointoil-novelty iii my preferred procese living' the'employment olf aroasting; step eiilisequeiitly to a leach step i'vlieiieter the 'valuesretained alter a leachisiii' ol" the ci'iiufia'iti'aties are 'tonnel towai'i'ciit this coiii'sef-i'he deterred roasting' living then followedhy a Siihtequeiit leaching'. llhat ie to say, have diecoveied that.,while the initial roaitii'igf oit Certain ciincei'it-i'atee, which maycoiitaiii,t'oi' example, hoi'iiite' oi' chalcocitc oi' chalcopi'i'ite.may yield :i caleine whose extraction very incomplete, theeii'iiih'iyinent of au initial leaching'.y followed by what. l haretermed deterred i'oaetiiig n ci,

inav Yield a caleine from which a nearly' complete siiliseipieiitextinction is; possible.

lfor eiaiiiplc, iii the exociiioii o't' my 'prow f ivii'oceei'l hyilii'iii' .tee in. which tho copper i923. Serial No. 639,963.

the forni of a sulfate, which may be present in quantities up to about4%, by fariiiliar re* actions, ot which the following may Serve as anexample:

requiring' more elevation of temperature than does chaleocite, andthisinitial extrae-- tion being' etten insutlieient for a satisfac toi'ilycomplete recovery ol' Values.-

'llhe residue being then separated, hy til-` ti'atioii oi' otherwise,from the leach liquor, l may roast the residue Without risk ofdetrimental eliiects referred to above, the leached concentrates beingthereby hi'iiiigl'it largely into au oxidized condition favorable 'to a'very complete extraction, and thiS extraction may he executed iii thesaine general iiiai'iiier an that already described, the reeultiiigtilti'ate being; optionally c iiihiiied with that tiret olitainedy andthe total quantity of i'ich liquor heilig then subjected to anelecti'i'ilys-iiii oi' to other treatment. adapted to the iiiroduc`tion'ot' either4 metallic copper or a desired compound thereof. l

li theeolublc iron content ot il trates iiiidei'ggoiiii; ti'eatiiieiithappens to be compai'ai'ively high, l may control ythe miaiilit)I ol"thi@` element hy any ymutable means, and certain advantageous methodstor thin` control are desci'il'ied in my impending' application Slet'.No. 639,970 tiled May i8, 19253.

lllhile the process to which the pres-eut application is directed doesnot necessitate the employment oi'I the additional invention mentionedabove, it; is advantageous, especialli' when metallic copper is the endproduct dcii'ed. to so conduct aii electrolysis, as to regenerate asuitable leach liquor eiii'mltaoeouely with the depordtiou of copper. :iSiiitahle quantity oli ii'oii .heiligl oxidii/ eih in' the action oi thecurrent, 'from the liii'm to the iei'i'ic loria, and anyaihlil'ioiis`oi" sull'ui'ic acid lieiiiyf :ieA may heiiifiii'atcd hyix'miparisoii ol the acid content of the regenerated liquor with theacid requirements oit' the concentrates.

liVhen the Concentrates which are under- Aeroine; treatment happen tovary in reducing action on ferrie iron, the relative quantity et suchiron which is transformed by electrolysis Afrom the ferrous to theferrie form may be regulated, mentioned in my copenrling applicationreferred to above by suitably proportioning the number ot graphiteaiiodes employed during electrode-position to the number of' anodestermed of lead or other material having a less elhciency iii theconversion referred to, the best ratio et graphite anodes to lead anodesbeing determined by experiment, and dependine; upon the relativequantity 'of ferrie iron which is found. suitable to the leaching' otthe concentrates in hand` a terric content in the leach liquor high as1% or more beingr desirable.

Although an important point ot the present application is the describedemployment ot a roasting; step interposed between two lea'clrine's, Imay ineulion herein` Yt'or the sake o: co,mpleteness` certainoutstandingY features of the invention described in my cope-udine,-application Ser. No. (5139.969 filed liay'llS, '1923 (Case ll). thementioned inventions being capable ol advantageous concurrent use in acyclical mannen-the residual liquors from the electrolytic tankscontaining tei-ric iron produced by reg-eueraiion, in quantitiessuitable'foi: use in tht` extraction of fresh batches ol material.

ln my last mentioned apiilieation, l have indicateiil the markedadi'ai'itag'es ot dry crushing` certain ores to a lineness adaptinglthem to pass a ver)v line mesh, such as a -lU inch mesh; but perhaps themost importan( and iiiteresliircr 'features ol the prooess set forththerein relate to a. maintainingr ol' the l'erric iron content. of myliquors at all times, throughout a cyclical process involving bothleaching and electr(ideposition, at a level determined by the bestellieiency ol such liquors when employed as leaching c. a gents.

As pointed ont -iii the' application referred to, up to the presenttime, electrolysis ot copper sulfato solutions carrying iron has .notbeen found practicable when so much iron is present that the stre 5th otterric. iron iiwidentally produced during `electroli'ises to a ligure inthe neighborhood ot' .3% o .51;11.. ,A

ln lui-ther explanation, it. may he stated that solutions 'airying` only.5%"t'o .5f/b1'- 'torrie iron are inactive on some suli'id com. poundsot coppe and, on others, the action is slow andinay even' requireheatinfi. vWith solutions containing larger amounts ot' l'ei'ric iron,saft7 "fi'oin .5',0 to,.75% or 123'?, or even more, l find the solventaction' is much more active and rapid, and on ores the necessity forwarming the solutions is thus obif'iated, with substantial sdram tages,from the standpoint olf economy. lt will be understood from the'foregoing that in the employment of ferrie sulfate lea-cn 4ingYsolutions, starting with, say 1% ferrie eonjointly my respectivediscoveries that such solutions are highly active solvents, and that itis practi -able to make them by eleccomplete reduction ot' the ferrieviron pi ent, aiming rallier to so proportion or@v and solvent that' avery complete extraction shall lakeplace while the per cent of ferrieiron present is still high enough to .act vigorously. rl`his point will,ot' course, vary with. ditiern ent. ores and coiidit.ioiis;'but, in freia, l have found it not necessary to reduce Edili i'errie iron belowabout .2%. a.nd,-iii seine cases below "ifI. Generally spealizing, onores, a maxiinnm strength ole 'iS/0 et iron is sullicient; but higherpercentages n be used` necessary. A preferred ine by which highpercentages of leiric may be made by electrolysis is rei'ierresubsequently herein.

As indicated above, a very important practical feat-nre et my inventionthe ii'iethod ot electrolysis by which l may preduce or regeneratelarger amounts et ferrie iron than have .hitherto l,been thoughtpossible at any reasonable cathode eli'icieney. The presence of ferrie ironduring electrolysis of copper solutions has been considered highlyobjectionable, and objeetiosiabl proportion to the amount' of ferriepresent. This viewlias appareiitl to aneppreeiation ot the tact eiron/is an etlicient solvent for in per; and unless means are taken toeormern yact the mentioned tendency to solution, 'the cathode efliciencyis correspondingly re duced. Statements are found in the literature tothe ellect that at, about .l% of tetris iron, depositi n etliciencybecomes very l and. as a practical proposition, at one installationusing` electrolysis, maximum rei rie iron is preferably held at about 1ilimits, the actual percentage ont ferrie iron they he diereVMedy-although obviously, the orerrtll elliciency, :tor s, given mnountof copper deposit, with e given current density, will very with thepoint at which ferrie .iron in beginning electrolysis. ln order,therefore, to maintain any constant Cleposi tion ein. j the umonnt ofcopper deposit ed must wry inrersciy with the merece pern centr je'irric iron before und sitter eleclor exemple, in en electrolysis withzero :terric iron. and ending it/0, shout .53% copper may he plated outut average over-:ill etliciency of about 59%; ond. storting with, srry,.8% and endwit1 'A ferrie iror shout .15% copper ed out et, the seineetllciency, un-

conditions described. v

with o. higher uverege of ferore, the solutions have tolle Lu .niortfrequently in order to leach oin any given quantity ot' ore. s is t ine:it en expense ot pumping cost, v nevertheless he entirely justified inriew o the foot that., usstzited, high tei.`- ric iron is very desirablepoint of leaching ellicieney.

'llo oiidize iron during' electrodeposition of como-er, ll here found itadvantageous to employ e current density ol at leest seven to eight:iroperes per square foot; und the current density may he raised tofifteen aniperes or more per ,square vfoot, depending on the "ric ine.cutliode eliciencv.

, llo ohtfein com mcrcielly protfihle wie" ls, as measured in terms oipouriels or copper 1per kilowatt hour., :it Dort-amt that low voltageshe employed; end such ifolteges may he ohtziined hf e. moderate heating(sity, to 110 degrees in connection with which it may he udyuntegcons toemploy known nieuns tot depolarization, end also 'to employ es lerneproportion ot graphite anodes as .they he consi stent with it dei'eri t.roasting is o'ttentlistinctly more advantageous then un initialroasting, it 1s ot the highest tecl'inicel interest that, in the.

'llhet is to soy, within the mentioned' troni the stendiron present,'with resulting conithe considerations in-v solvingA und cleetrolyticprocess are obtainable by s incre cold extraction 'tor by u coldlextraction followed hy Wurm Ycxtimt.on,--y

depending ou the nuturoot the sul lids iorcsu ent) this lustn'ientioi'ied variation ol my process. which muy justify n working; ofex tcnsive bodies ot ore that here heen regarded as practicallyvelue-less, niz'ly he ot the very greatest economic importance.

lt will hc understood that Various :teetures of luy present inventionmuy he inde pendently used and various niodiliciitions in the processdescribed may he nitide hy those skilled in the nrt without departureiroin the spirit und scope ot my present inve tion as the suine isindicated in the torelgoing description und in thc :Following claims.

l The single ligure of the diewingis u loW sheet of the processTheugitation app ratos l receives the concentrates and the leachliquor,'wl1ich is drown oil' into the, settling uppiirzitus troni whicliit passed through the line 3 to the tunk house 'llhc solids pass fromthe settling apparatus 2 to :i dryer 5 Iend thence to e rooster 6. lheroasted' product posses to u second agitation apparatus T and thence toa second settling apparatus 8, whence the liquor ,posses through u lineel to the tenir house'. l'n the tank house the solution is elcctrolyzedund -the liquor returned by the lines 9 und l() to the two agitationapparatus l und 7. 'l'.he heavy line ll indicates the flow of the concentrutes, which becomes the residue flowing; out from. the secondsettling; apparatus through the vline l2. Thus we have, first, agitationofy the concentrates with a leaching solution; second, settling 'forrecovering the copperliquor and porti-illy treated concentrates; third,electrolysis oit the copper liquor und return to the first agitationtuch; fourth, drying the thickened, partially treated material; fifth,roasting such nieteriel; sixth, agitutingthe roested product withe'leeching solution; seventh, settling to recover the copper liquor andthe thief cned barren residues and passino; the letter.' oil? to'Washing and inel discharge sind eighth, electrolysis of the liquor fromthe second settlingl tank and, return of it to the /l-pf tain coppertherefrom, the proceure which loo lllii llo . roasting and then by afurther ferrous sulfate being comprises an initial leaching followed bytain copper therefrom, the procedure which comprises'an initial leachingfollowed by a roasting and then by a further leaching, the liquorbeing;` regenerated by a subsequent electrolysis.

5. 'In the treating` of concentrates to obtain copper therefrom, theprocedure which comprises an initial leaching followed by a leaching,the liquor being regenerated by a subsequent electrolysis en'iploying ananode containing graphite. l

6. In the treating of concentrates to obtain copper therefrom, theprocedure which comprises an initial leaching followed by a roasting andthen by a furtherle ching` the liquor being regenerated by a. subsequentelectrolysis employing` a current density of ten or more amperes persquare foot 7. In the treating of concentrates to obtain coppertherefrom, the procedure which comprises an initial leachingl followedby a roasting and then by a further lea-ching, the liquor being;regenerated by a subsequent electrolysis with an agitation'and :i tenuperature above atmospheric.'

8. n the treating ot' concentrates to ob tain copper therefromntheprocedure which comprises an initial leaching followed by a roasting andthen by a further leaching, the liquor beine' regenerated by asubsequent electrolysis with au agitation and a teniperature aboveatmospheric, and suflicient present during electrolysis to act as adepolarizer.

9. In the treating of concentrates to obcomprises an initial leachingfollowed by etliciency of extraction.

l2. In the treating of concentrates to ob` essere mospheric, there beingsinlieient of a fer "1 rous salt present during electrolysis to acl. asal depolarizer, and the residual liquors being employed in the.subsequent leaching` of additional concentrates.

l0. In the treating of concentrates to obv tain copper therefrom, theprocedure which by a roasting and then by a further leaching, the ferriecontent of liquors being kept throughout at a level determined byefliciency of extraction.

ll. In the treating of concentrates to obtain copper therefron'i, theprocedure which' comprises an initial leachingr followed by a roastingand then by a liquor being regenerated by a subsequent electrolysis andthe ferrie content thereof being kept throughout at a level tain coppertherefrom, the procedure which comprises an initial leaching followed bya roasting and then by a further liquor being regenerated by asubsequent electrolysis employing an anode containing graphite and theferriccontent of the liquor beingl kept throughout at a level determinedby efficiency of extraction.

In testimony hereotl l have signed my name to this specification.

GEORGE l); VAN ARSl'ALlx..

further leaching, the

determined leaching, the

